Who is the Colorado Nutrient Who is the Colorado Nutrient Who is - - PowerPoint PPT Presentation

Who is the Colorado Nutrient Who is the Colorado Nutrient Who is the Colorado Nutrient Who is the Colorado Nutrient Coalition and Why are we Coalition and Why are we h ? h ? here? here?

John C. Hall John C. Hall William T. Hall William T. Hall William T. Hall William T. Hall Tad S. Foster Tad S. Foster

The Science The Science Where does it stand? Where does it stand? Where does it stand? Where does it stand?

Review of Mechanisms Review of Mechanisms Review of Mechanisms Review of Mechanisms I nfluencing Nutrient I nfluencing Nutrient D i i L k d D i i L k d Dynamics in Lakes and Dynamics in Lakes and Streams Streams

EPA GUI DANCE ON ALGAL EPA GUI DANCE ON ALGAL GROWTH RELATI ONSHI P

“The difficulty associated with understanding predictive relationships between nutrient loading and algal biomass is perhaps the biggest challenge to establishing meaningful nutrient criteria.”

(Nutrient Criteria Technical Guidance Manual–Rivers and ( Streams at 73)

CLARK FORK RI VER (MT) ( ) NUI SANCE ALGAE (CLADOPHERA)

Relative Cladophora abundance in the Clark Fork River, MT. Abundance Scores: VA = very abundant, A = Abundant, VC = Very Common, C = Common, R = Rare, N = not present. (Dodds et al. 1997)

NUTRI ENT CRI TERI A NUTRI ENT CRI TERI A NUTRI ENT CRI TERI A NUTRI ENT CRI TERI A DEVELOPMENT CONSI DERATI ONS DEVELOPMENT CONSI DERATI ONS

• Nutrients (N, P) not toxic in classical sense

Nutrients (N, P) not toxic in classical sense

– No direct effect on invertebrates directly No direct effect on invertebrates directly – Stimulate plant growth Stimulate plant growth  adverse effects adverse effects

• EPA Nutrient Criteria Guidance (2000)

EPA Nutrient Criteria Guidance (2000) EPA Nutrient Criteria Guidance (2000) EPA Nutrient Criteria Guidance (2000)

– Define relationship to plants, D.O., pH, etc. Define relationship to plants, D.O., pH, etc. – Set causal (TP) and response (Chl ‘a’) criteria Set causal (TP) and response (Chl ‘a’) criteria ( ) p ( ) ( ) p ( )

• Recent Regulatory Actions

Recent Regulatory Actions

– Stressor Stressor-Response Empirical Analysis Response Empirical Analysis - SAB SAB Stressor Stressor Response Empirical Analysis Response Empirical Analysis SAB SAB – Florida WQS Problems Florida WQS Problems

NUTRI ENT CRI TERI A MUST NUTRI ENT CRI TERI A MUST NUTRI ENT CRI TERI A MUST NUTRI ENT CRI TERI A MUST CONSI DER PLANT GROWTH CONSI DER PLANT GROWTH

[F]ish and macroinvertebrates do not directly respond to nutrients, and therefore may not be as sensitive to changes in nutrient l l bl d d h l concentrations as algal assemblages. It is recommended that relations between biotic integrity of algal assemblages and nutrients be defined and then related to biotic integrity of macroinvertebrate and fish assemblages in a stepwise, mechanistic fashion. assemblages in a stepwise, mechanistic fashion. (EPA. 2000. Nutrient Criteria Technical Guidance Manual - Rivers and Streams at 85)

SAB CONCLUSI ON OVERVI EW SAB CONCLUSI ON OVERVI EW SAB CONCLUSI ON OVERVI EW SAB CONCLUSI ON OVERVI EW

• Regression Approach Not Scientifically Defensible for

Regression Approach Not Scientifically Defensible for g pp y g pp y Nutrient: Invertebrates; Lacks Cause/Effect Demonstration Nutrient: Invertebrates; Lacks Cause/Effect Demonstration

• Need to Confirm “Impairment” Thresholds Are Biologically

Need to Confirm “Impairment” Thresholds Are Biologically p g y p g y Significant Significant

• Need to Account for Factors Influencing Nutrient Dynamics

Need to Account for Factors Influencing Nutrient Dynamics Need to ccou t o acto s ue c g Nut e t y a cs Need to ccou t o acto s ue c g Nut e t y a cs and Invertebrate Metrics (Habitat, DO, pH, Scour/Sediment) and Invertebrate Metrics (Habitat, DO, pH, Scour/Sediment)

• Loading Approach May Be a Better Than Concentration

Loading Approach May Be a Better Than Concentration Loading Approach May Be a Better Than Concentration Loading Approach May Be a Better Than Concentration

• Failure to Consider Site

Failure to Consider Site-

• specific Data May Yield Inappropriate

specific Data May Yield Inappropriate Results Results Results Results

EVALUATI ON OF EVALUATI ON OF COLORADO’S COLORADO’S NUTRI ENT CRI TERI A NUTRI ENT CRI TERI A PROPOSAL PROPOSAL PROPOSAL PROPOSAL

BASI C CONCERNS WI TH BASI C CONCERNS WI TH COLORADO APPROACH COLORADO APPROACH

• No demonstrated need for TN control in all

No demonstrated need for TN control in all Lakes and Streams Lakes and Streams

• Lakes

Lakes – – regression approach fails to reflect regression approach fails to reflect multiple factors controlling plant growth multiple factors controlling plant growth u t p e acto s co t o g p a t g o t u t p e acto s co t o g p a t g o t

• Streams

Streams – – regression approach alone regression approach alone contrary to SAB findings contrary to SAB findings – no cause and no cause and contrary to SAB findings contrary to SAB findings no cause and no cause and effect effect

NO NEED FOR UNI VERSAL NO NEED FOR UNI VERSAL TN CONTROL TN CONTROL

When evaluating the relationships among nutrients and algal response When evaluating the relationships among nutrients and algal response within stream systems, it is important to first understand which nutrient is

• limiting. Once the limiting nutrient is defined, critical nutrient

concentrations can be specified and nutrient and algal biomass relationships can be examined to identify potential criteria to avoid nuisance algal levels.

• EPA. 2000. Nutrient Criteria Technical Guidance Manual – Rivers and Streams,

at 74. (Emphasis added) at 74. (Emphasis added) Many natural factors combine to determine rates of plant growth in a

• waterbody. First of these is whether sufficient phosphorus and nitrogen

i t t t l t th Th b f f th t i t exist to support plant growth. The absence of one of these nutrients generally will restrict plant growth. I n inland waters, typically phosphorus is the limiting nutrient of the two, because blue-green algae can “fix” elemental nitrogen from the water as a nutrient source. g

• EPA. 1999. Protocol for Developing Nutrient TMDLs First Edition at t 2-
• 4. EPA 841-B-99-007 (Emphasis added)

S LAKES LAKES

SAB CONLCUSI ON RELEVANT TO SAB CONLCUSI ON RELEVANT TO LAKES PROPOSAL LAKES PROPOSAL

Plant biomass is driven by nutrient supply rates (i.e., nutrient mass loads). Plant biomass is driven by nutrient supply rates (i.e., nutrient mass loads). Ambient nutrient concentrations are not necessarily good surrogates for Ambient nutrient concentrations are not necessarily good surrogates for nutrient mass loads nutrient mass loads Relationships between nutrient mass loads and Relationships between nutrient mass loads and nutrient mass loads. nutrient mass loads. Relationships between nutrient mass loads and Relationships between nutrient mass loads and ambient nutrient concentrations are highly system ambient nutrient concentrations are highly system-

• specific and depend

specific and depend

• n many factors including inflows, hydrology, bathymetry, sediment
• n many factors including inflows, hydrology, bathymetry, sediment-
• water exchanges and chemical

water exchanges and chemical-

• biological processes.

biological processes. Consequently, there Consequently, there may be many systems for which nutrient concentrations will not be may be many systems for which nutrient concentrations will not be may be many systems for which nutrient concentrations will not be may be many systems for which nutrient concentrations will not be appropriate stressor variables appropriate stressor variables. For such systems it may be more For such systems it may be more appropriate, and scientifically defensible, to use site appropriate, and scientifically defensible, to use site-

• specific mechanistic

specific mechanistic models incorporating loading to determine the nutrient controls required to models incorporating loading to determine the nutrient controls required to attain designated uses (at 11) attain designated uses (at 11) attain designated uses. (at 11) attain designated uses. (at 11)

LAKE CRI TERI A LAKE CRI TERI A LAKE CRI TERI A LAKE CRI TERI A

Use Class Use Class TP TP TN TN Chl Chl-

• a

a Cold Cold 24 ug/L 24 ug/L 490 ug/L 490 ug/L 8 ug/L 8 ug/L Cold Cold 24 ug/L 24 ug/L 490 ug/L 490 ug/L 8 ug/L 8 ug/L Warm Warm 82 ug/L 82 ug/L 960 ug/L 960 ug/L 20 ug/L 20 ug/L

• Cold Lakes: Chl

Cold Lakes: Chl-

• a optimal for most salmonids

a optimal for most salmonids

• Warm Lakes: Chl

Warm Lakes: Chl-a optimal for game fish a optimal for game fish Warm Lakes: Chl Warm Lakes: Chl a optimal for game fish a optimal for game fish

• TP/TN: linear regression of cold/warm lakes to

TP/TN: linear regression of cold/warm lakes to achieve chl achieve chl-a criterion. a criterion. achieve chl achieve chl a criterion. a criterion.

COLORADO LAKE APPROACH COLORADO LAKE APPROACH COLORADO LAKE APPROACH COLORADO LAKE APPROACH

• Chlorophyll

Chlorophyll-

• a criteria

a criteria

– Good approach (biologically significant), but Good approach (biologically significant), but

l l k ( h) l l k ( h)

• Only two lake categories (not enough)

Only two lake categories (not enough)

• Need more use categories/chl ‘a’ standards

Need more use categories/chl ‘a’ standards

• Inappropriate averaging period (July

Inappropriate averaging period (July-

• Sept vs Growing

Sept vs Growing Season) Season)

• TP Criteria

TP Criteria

U d li it d i h ( U d li it d i h (SAB iti i ) SAB iti i ) – Used limited regression approach ( Used limited regression approach (SAB criticism) SAB criticism) – Site Site-

• specific data show different result

specific data show different result

OTHER FACTORS OTHER FACTORS I NFLUENCI NG CHL’a’ TARGETS I NFLUENCI NG CHL’a’ TARGETS

• Nature of water body

Nature of water body

– Natural or man Natural or man-

• made

made – Shallow or deep Shallow or deep – Warm or cold, elevation Warm or cold, elevation

• Type of fishery

Type of fishery

• Size of watershed (e.g., Lower S. Platte)

Size of watershed (e.g., Lower S. Platte)

• Controlling use (aquatic life, drinking

Controlling use (aquatic life, drinking water, agricultural) water, agricultural)

CARP I NFLUENCE CARP I NFLUENCE ALGAL GROWTH ALGAL GROWTH ALGAL GROWTH ALGAL GROWTH

AVERAGI NG PERI OD AVERAGI NG PERI OD AVERAGI NG PERI OD AVERAGI NG PERI OD

Cherry Creek Monthly Chlorophyll-a March 1997 - September 2008 20 25 30 L)

Suggested Warm Water Criterion

5 10 15 20 Chl-a (ug/L 5 April May June July Aug Sept Oct

Overview of Water Quality Overview of Water Quality M d l Ki i M d l Ki i Model Kinetics Model Kinetics

CONCERN WI TH REGRESSI ON CONCERN WI TH REGRESSI ON APPROACH USI NG 80 APPROACH USI NG 80TH

TH % I LE

% I LE

• Pairing of highest 80

Pairing of highest 80th

th percentile Chl

percentile Chl-

• a and

a and TP concentrations from summer averages TP concentrations from summer averages likely to misrepresent actual lake response likely to misrepresent actual lake response

• Reduction of all data into a single point

Reduction of all data into a single point

• bscures variability and provides a false
• bscures variability and provides a false
• bscu es

a ab y a d p o des a a se

• bscu es

a ab y a d p o des a a se sense of validity sense of validity

Chl Chl-

• a vs. TP for EMAP Northeast Lakes Survey

a vs. TP for EMAP Northeast Lakes Survey

(Empirical Approaches for Nutrient Criteria Derivation, (Empirical Approaches for Nutrient Criteria Derivation, (Empirical Approaches for Nutrient Criteria Derivation, (Empirical Approaches for Nutrient Criteria Derivation, USEPA 2009) USEPA 2009)

Chl-a=15 ug/L

TP=16 TP=64

ACTUAL COLD WATER ACTUAL COLD WATER LAKE DATA LAKE DATA

Bear Creek (1991 - 2008 Summer Average) 80

y = 162.28x0.7448 R2 = 0.2602

40 50 60 70 (ug/L) 10 20 30 40 Chl-a (

Summer Average 80th Percentile Median Average Regression-TP>0.04 Regression

0.000 0.050 0.100 0.150 0.200 0.250 TP (mg/L)

R2=0.26; 80th percentile overestimates regression by 50%

ACTUAL COLD WATER ACTUAL COLD WATER LAKE DATA LAKE DATA

Dillon (1981 - 2008 Summer Average) 10

y = 91.926x0.6116 R2 = 0.0657

5 6 7 8 9 (ug/L)

Summer Average 80th P til

1 2 3 4 5 Chl-a (

80th Percentile Median Average Regression

0.000 0.002 0.004 0.006 0.008 0.010 0.012 TP (mg/L)

R2=0.07; 80th percentile overestimates regression by 33%

ACTUAL COLD WATER ACTUAL COLD WATER LAKE DATA LAKE DATA

Granby (1989 - 2008 Summer Average) 10 5 6 7 8 9 (ug/L)

Summer Average 80th Percentile Median Average Regression y = 1.2561x-0.186 R2 = 0.0324

1 2 3 4 5 Chl-a (

g

0.000 0.010 0.020 0.030 0.040 0.050 0.060 0.070 TP (mg/L)

R2=0.03; 80th percentile overestimates regression by 100% Proposed TP WQS – 0.024 mg/l not needed

ACTUAL COLD WATER ACTUAL COLD WATER LAKE DATA LAKE DATA

Shadow Mountain (1989 - 2008 Summer Average) 16 18 8 10 12 14 16 a (ug/L)

Summer Average 80th Percentile Median Average Regression y = 1.4223x-0.2885 R2 = 0.0309

2 4 6 8 Chl-a 0.000 0.010 0.020 0.030 0.040 0.050 0.060 TP (mg/L)

R2=0.03; 80th percentile overestimates regression by 100%

ALTERNATE REGRESSI ON ALTERNATE REGRESSI ON ALTERNATE REGRESSI ON ALTERNATE REGRESSI ON

24 UG/ L TARGET I NAPPROPRI ATE 24 UG/ L TARGET I NAPPROPRI ATE

Cold Water Lakes Summer Average Observations for Dillon, Granby, and Shadow Mountain

R2 = 0 0243

10 100 ug/L)

R = 0.0243

0 1 1 Chl-a ( 0.1 0.001 0.01 0.1 TP (mg/L)

ACTUAL WARM WATER ACTUAL WARM WATER LAKE DATA LAKE DATA

Cherry Creek (1997 - 2008 Summer Average) 30

y = 2.5993x-0.8573 R2 = 0.2931

15 20 25 30 (ug/L)

Summer Average 80th Percentile Median

5 10 15 Chl-a (

Median Average Regression

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 TP (mg/L)

R2=0.29; 80th percentile overestimates regression by 33%

WARM WATER VARI ABI LI TY WARM WATER VARI ABI LI TY WARM WATER VARI ABI LI TY WARM WATER VARI ABI LI TY

Colorado Warm Water Lakes

1000 10 100 Chl-a (ug/L)

90th %ile Confidence Interval

Chl-a Target

1 0.001 0.01 0.1 1 TP (mg/L)

Regression Lower Confidence Limit Upper Confidence Quincy Standley Aurora Barr Milton

Confidence I nterval for 20 ug Chl-a/ L: 50 – 300 ug TP/ L

SUMMARY OF LAKE MECHANI SMS SUMMARY OF LAKE MECHANI SMS TO CONSI DER I N CRI TERI A DERI VATI ON TO CONSI DER I N CRI TERI A DERI VATI ON

• Chl

Chl-

• a Threshold

a Threshold

– Use designation Use designation

• Aquatic life

Aquatic life

• Factors affecting TP

Factors affecting TP-

• Algal

Algal biomass relationship biomass relationship

– Areal loading rate Areal loading rate

Aquatic life Aquatic life

• Drinking water

Drinking water

• Agricultural

Agricultural

– Fishery type Fishery type Areal loading rate Areal loading rate – Transparency Transparency – Residence time Residence time Th l t tifi ti Th l t tifi ti Fishery type Fishery type

• Cold

Cold

• Warm

Warm

• Rough (carp/bullheads)

Rough (carp/bullheads)

– Thermal stratification Thermal stratification – Aquatic life Aquatic life

• Bottom

Bottom-

• feeding fish

feeding fish

• Rough (carp/bullheads)

Rough (carp/bullheads)

– Morphology Morphology

• Depth

Depth

• Si e of

ate shed Si e of ate shed

• Grazer population

Grazer population

– Sediment kinetics Sediment kinetics – Emergent Plants Emergent Plants

• Size of watershed

Size of watershed

• Natural vs Man

Natural vs Man-

• made

made

g

SUGGESTED LAKE APPROACH SUGGESTED LAKE APPROACH SUGGESTED LAKE APPROACH SUGGESTED LAKE APPROACH

• Set chl ‘a’ targets to fit primary use/physical

Set chl ‘a’ targets to fit primary use/physical setting for each reservoir setting for each reservoir

• Unmanaged lakes use AQ life protection

Unmanaged lakes use AQ life protection

• Chose range of acceptable TP concentration to

Chose range of acceptable TP concentration to meet target meet target

• Use site

Use site-

• specific data to pick value within range

specific data to pick value within range

• Outside of range

Outside of range – – site specific standard site specific standard

• TN Control

TN Control – – site specific determination site specific determination

STREAMS STREAMS STREAMS STREAMS

SAB CONCLUSI ONS RELEVANT TO SAB CONCLUSI ONS RELEVANT TO STREAM PROPOSAL STREAM PROPOSAL

[T]he final document should clearly state that statistical [T]he final document should clearly state that statistical associations may not be biologically relevant and do not prove associations may not be biologically relevant and do not prove associations may not be biologically relevant and do not prove associations may not be biologically relevant and do not prove cause and effect. (at 2) cause and effect. (at 2) Without a mechanistic Without a mechanistic understanding and a clear causative link understanding and a clear causative link between nutrient between nutrient levels and impairment, there is levels and impairment, there is no assurance no assurance that managing that managing p , p , g g g g for particular nutrient levels for particular nutrient levels will lead to the desired outcome will lead to the desired outcome. . (at 4); The Guidance needs to clearly indicate that the (at 4); The Guidance needs to clearly indicate that the empirical stressor empirical stressor-

• response approach

response approach does not result in cause does not result in cause-

• ff

t l ti hi ff t l ti hi it l i di t l ti th t it l i di t l ti th t d t d t effect relationships effect relationships; it only indicates correlations that ; it only indicates correlations that need to need to be explored further be explored further. (at 39) (at 39)

STREAM CRI TERI A STREAM CRI TERI A STREAM CRI TERI A STREAM CRI TERI A

Use Class Use Class TP TP TN TN MMI MMI Cold Cold 90 ug/L 90 ug/L 824 ug/L 824 ug/L 66.5 66.5 Cold Cold 90 ug/L 90 ug/L 824 ug/L 824 ug/L 66.5 66.5 Warm Warm 135 ug/L 135 ug/L 1,316 ug/L 1,316 ug/L 57 57

• MMI targets based on 5% reduction from Reference Stream median MMI

MMI targets based on 5% reduction from Reference Stream median MMI

• Anchor Point set at 85%ile of Reference Stream nutrient concentration

Anchor Point set at 85%ile of Reference Stream nutrient concentration TP/TN li i f Ob d Bi l i l P t ti l TP/TN li i f Ob d Bi l i l P t ti l

• TP/TN: linear regression of Observed Biological Potential

TP/TN: linear regression of Observed Biological Potential Observation: Observation: Nutrient control occurs ABOVE saturation growth rate Nutrient control occurs ABOVE saturation growth rate concentration so no effect on plant growth level expected concentration so no effect on plant growth level expected

COLORADO STREAM COLORADO STREAM APPROACH APPROACH

• MMI targets

MMI targets

– Biologically significant, but Biologically significant, but – No demonstrated relationship to TP No demonstrated relationship to TP – Significant influence of confounding factors Significant influence of confounding factors

Pl t G th I d Pl t G th I d

• Plant Growth Ignored

Plant Growth Ignored

• TP Criteria

TP Criteria

B d i h ( B d i h ( SAB fi di ) SAB fi di ) – Based on regression approach ( Based on regression approach (≠SAB findings) ≠SAB findings) – Mechanistic Model Needed Mechanistic Model Needed

RELATI ONSHI P BETWEEN NUTRI ENTS RELATI ONSHI P BETWEEN NUTRI ENTS AND BENTHI C LI FE I MPAI RMENT AND BENTHI C LI FE I MPAI RMENT AND BENTHI C LI FE I MPAI RMENT AND BENTHI C LI FE I MPAI RMENT

Flow Light Nutrients Periphyton Benthic biotic indices indices Grazers

Pesticides, Herbicides, Metals, etc.

Sedimentation Substrate

CONSI DERATI ON OF FACTORS CONSI DERATI ON OF FACTORS I NFLUENCI NG NUTRI ENT I NFLUENCI NG NUTRI ENT DYNAMI CS/ I MPAI RMENT METRI C DYNAMI CS/ I MPAI RMENT METRI C,

, SAB Report SAB Report

For criteria that meet EPA’s stated goal of “protecting against For criteria that meet EPA’s stated goal of “protecting against environmental degradation by nutrients,” the underlying causal environmental degradation by nutrients,” the underlying causal models must be correct. models must be correct. Habitat condition is a crucial Habitat condition is a crucial consideration in this regard (e.g., light [for example, canopy consideration in this regard (e.g., light [for example, canopy cover], hydrology, grazer abundance, velocity, sediment type) cover], hydrology, grazer abundance, velocity, sediment type) that is not adequately addressed in the Guidance that is not adequately addressed in the Guidance. Thus, a . Thus, a major uncertainty inherent in the Guidance is accounting for major uncertainty inherent in the Guidance is accounting for j y g j y g factors that influence biological responses to nutrient inputs. factors that influence biological responses to nutrient inputs. Addressing this uncertainty requires adequately accounting Addressing this uncertainty requires adequately accounting for these factors in different types of water bodies for these factors in different types of water bodies. (at 36,37) . (at 36,37) f f ff yp f f f ff yp f ( ) ( )

PERI PHYTON: TP PERI PHYTON: TP RELATI ONSHI P UPDATE RELATI ONSHI P UPDATE

Dodds (2006) Dodds (2006) Attached algae might be able to attain impressive bio Attached algae might be able to attain impressive bio-

• mass in nutrient

mass in nutrient poor water because periphyton can poor water because periphyton can mass in nutrient mass in nutrient-poor water because periphyton can poor water because periphyton can use the small amounts of nutrients that continuously use the small amounts of nutrients that continuously flow by. flow by. flow by. flow by. Paul and Zheng (2007) Paul and Zheng (2007) g ( ) g ( ) The highest algal biomass [in PA targeted watersheds] The highest algal biomass [in PA targeted watersheds]

• ccurred at sites where TP concentrations were
• ccurred at sites where TP concentrations were

relatively low (14 relatively low (14 – 35 35 µ µg/L). [ g/L). [Upstream of POTWs Upstream of POTWs]

Plant Growth Saturation

REFERENCE STREAMS CONFI RM REFERENCE STREAMS CONFI RM NO TP I MPACT ON MMI NO TP I MPACT ON MMI

C l d C ld W t R f Ri d St Colorado Cold Water Reference Rivers and Streams 70 80 90 100

Data Anchor Point Average

30 40 50 60 70 MMI 10 20 0.001 0.01 0.1 1 Whisker = 1 Standard Deviation TP (mg/L)

MMI for reference streams below Anchor Point not significantly different from MMI for reference streams below Anchor Point not significantly different from results for references streams above Anchor Point (P=0.92). Conclude that TP is not a stressor for MMI.

COLD WATER STREAMS COLD WATER STREAMS COLD WATER STREAMS COLD WATER STREAMS

Colorado Cold Water Rivers and Streams: MMI vs Inst TP Colorado Cold Water Rivers and Streams: MMI vs Inst TP 70 80 90 20 30 40 50 60 70 MMI 10 20 5 9 1 1 1 5 2 2 1 3 3 5 4 5 6 9 1 5

RESULTS No Significant Difference for TP Concentrations in the range of 0.015 - 6.0 mg/L

.

• .

. 5

• .

. 9

• .

1 . 1 1

• .

1 . 1 5

• .

2 . 2

• .

2 . 2 1

• .

3 . 3

• .

3 . 3 5

• .

4 . 4 5

• .

6 . 6

• .

9 . 9

• .

1 5 . 1 5

• 6

. Bin (TP-Inst Range - mg/L) Bin (TP-Inst Range - mg/L)

WARM WATER STREAMS WARM WATER STREAMS WARM WATER STREAMS WARM WATER STREAMS

Colorado Warm Water Rivers and Streams: MMI vs Inst TP 70 80 20 30 40 50 60 70 MMI

S S

10 20 . 2 1 . 3 6 6 . 5 4 4 . 9 . 1 3 5 . 1 9 6 6 . 2 5 . 3 4 . 4 6 . 5 9 . 8 1 1 . 2 6 4 .

RESULTS No Significant Difference for TP Concentrations in the range of 0.090 - 1.26 mg/L

.

• .

2 1

• .

3 6

• .

5 4

• .

9

• .

1 3 5

• .

1 9 6

• .

2 5

• .

3 4

• .

4 6

• .

5 9

• .

8 1

• 1

1 . 2 6

• 4

Bin (TP-Inst Range - mg/L)

BI OLOGI CAL SI GNI FI CANCE/ USE BI OLOGI CAL SI GNI FI CANCE/ USE I MPAI RMENT THRESHOLD RELATI ONSHI P I MPAI RMENT THRESHOLD RELATI ONSHI P I MPAI RMENT THRESHOLD RELATI ONSHI P, I MPAI RMENT THRESHOLD RELATI ONSHI P,

SAB Report SAB Report

• The Committee emphasizes the importance of choosing the biological

The Committee emphasizes the importance of choosing the biological endpoints (i.e., response variables) that respond endpoints (i.e., response variables) that respond specifically to specifically to i W h f W h f b hi i di b l d b hi i di b l d nutrients

• nutrients. We note that responses of

. We note that responses of benthic indices can be related to benthic indices can be related to many types of stress many types of stress. We question why periphyton would not be a . We question why periphyton would not be a better receptor to measure. (at 15) better receptor to measure. (at 15)

• Large uncertainties

Large uncertainties in the stressor in the stressor-

• response relationship and the fact

response relationship and the fact that causation is neither directly addressed nor documented indicate that causation is neither directly addressed nor documented indicate that the that the stressor stressor-response approach using empirical data cannot be response approach using empirical data cannot be that the that the stressor stressor-response approach using empirical data cannot be response approach using empirical data cannot be used in isolation to develop technically defensible water quality used in isolation to develop technically defensible water quality criteria criteria that will “protect against environmental degradation by that will “protect against environmental degradation by nutrients.” (at 37; see also 22) nutrients.” (at 37; see also 22) ( ) ( )

CONFOUNDI NG FACTORS CONFOUNDI NG FACTORS MUST BE CONSI DERED MUST BE CONSI DERED

16th Annual Meeting of the California Aquatic Bioassessment Workgroup (October, 2009)

COVARYI NG FACTORS MUST COVARYI NG FACTORS MUST BE CONSI DERED BE CONSI DERED

Covariance of Covariance of Stream TP with Stream TP with TSS (Panhandle TSS (Panhandle Region Region -

• Florida)

Florida)

SUGGESTED MODI FI CATI ON TO SUGGESTED MODI FI CATI ON TO I NI TI AL PROPOSALS I NI TI AL PROPOSALS

• Use Narrative Approach to Set Site

Use Narrative Approach to Set Site-

• Specific TN Standards

Specific TN Standards Where Necessary to Protect Uses Where Necessary to Protect Uses

• Lake Approach Likely Both Over/Under Protective

Lake Approach Likely Both Over/Under Protective

• Set Additional Subcategories for Lakes and Reservoirs

Set Additional Subcategories for Lakes and Reservoirs

• Consider Site

Consider Site-

• Specific Reservoir Uses and Watershed Factors

Specific Reservoir Uses and Watershed Factors in Setting Chlorophyll in Setting Chlorophyll-

• a Standards

a Standards g p y g p y

• Set Range of Acceptable TP Concentrations and Use Site

Set Range of Acceptable TP Concentrations and Use Site-

• Specific Water Body Response Data to Select TP Value

Specific Water Body Response Data to Select TP Value

• Streams

Streams – Determine Trigger Value Considering SAB Determine Trigger Value Considering SAB gg g gg g Recommendations Recommendations

• Use Site

Use Site-

• Specific Data To Confirm Nutrient Related Impacts

Specific Data To Confirm Nutrient Related Impacts